[postgis-users] transform() does not do work for NGO1948 zone III-> WGS84 longlat (epsg:27393->epsg:4326)

[strk at refractions.net]

On Wed, Dec 21, 2005 at 10:10:01AM -0000, Mark Cave-Ayland wrote:
> 
> > -----Original Message-----
> > From: postgis-users-bounces at postgis.refractions.net [mailto:postgis-users-
> > bounces at postgis.refractions.net] On Behalf Of strk at refractions.net
> > Sent: 21 December 2005 08:19
> > To: PostGIS Users Discussion
> > Subject: Re: [postgis-users] transform() does not do work for NGO1948 zone
> > III-> WGS84 longlat (epsg:27393->epsg:4326)
> > 
> > On Tue, Dec 20, 2005 at 04:56:47PM -0500, Frank Warmerdam wrote:
> > ...
> > > Error -38 is:
> > >  	"failed to load NAD27-83 correction file",  	/* -38 */
> > >
> > > So basically, if the datum shift files are not found, then the
> > > code fallback to trying a conversion without the datum shift.
> > 
> > Thank you Frank,
> > maybe we should raise a WARNING in that case ? I mean, is
> > "shift files not found" condition a sign of incomplete
> > installation of PROJ4 ?
> 
> I would say a warning should definitely be given if the transformation being
> done is not the one that was requested by the user.

I've added the warning:

	elog(WARNING, "transform: failed to load NAD27-83 correction file");

But, I cannot reproduce the problem with this query:

	select AsText(
		transform('SRID=27393;POINT(2836.394208896 185526.991186176)',
			4326)
	);

Even if I temporarly remove /usr/local/share/proj  ...
Output is:

	POINT(0.0464201635443672 59.6661916850467)

postgis_proj_version(): Rel. 4.4.8, 3 May 2004

Tips on how to reproduce the error (or is it possible PROJ4 would
make the two attempts by itself ?) ?

--strk;